Multidisciplinary Approach to Identify and Mitigate the Hazard from

Induced Seismicity in Oklahoma Aus$n  Holland,  Randy  Keller,  Amberlee  

Darold,  Kyle  Murray,  Steve  Holloway,  Kevin  Crain  

Acknowledgements

Oklahoma  Secretary  of  Energy  and  Environment    Oklahoma  Corpora8on  Commission    OU  Mewbourne  College  of  Earth  and  Energy    

Industry  contributors  to  RPSEA  and  fault  database    Oklahoma  Independent  Petroleum  Associa8on  (OIPA)  

USGS  –  providing  many  different  temporary  seismic  sta8ons    

Oklahoma’s Increase in Earthquakes Earthquake rates per year

0.1  

3  

24  

Magnitude  4  or  Greater  Earthquakes  

Years  1882-­‐2008  

Years  2009-­‐2013  

Year  2014  

1.6   20  

42  

67  

40  

109  427  

Magnitude  3  or  Greater  Earthquakes  

Years  1980-­‐2008  

Year  2009  

Year  2010  

Year  2011  

Year  2012  

Year  2013  

Year  2014  Updated  Oct.  20,  2014  

Earthquake Forecasting •  Probability  of  one  or  more  earthquakes  of  magnitude  (m)  over  the  specified  $me  

•  Not  a  predic$on,  but  a  forecast  

Oklahoma Recurrence Rates & Probabilities

Calculated  with  a  6  month  moving  window  

Mc=1.9   Mc=2.3  

Oklahoma Earthquakes 2009-2014

Area  of  greatest  increase  is  about  15%  of  Oklahoma.  Captures  areas  of  significant  waste-­‐water  disposal  wells  

Cumulative Seismicity in Oklahoma Cu

mula8

ve  Num

ber  o

f  Earthqu

akes  

Oklahoma  Geol.  Survey  www.okgeosurvey1.gov/pages/earthquakes/catalogs.php  

UIC Class II Injection

Oklahoma Earthquakes 2009-2014

Area  of  greatest  increase  is  about  15%  of  Oklahoma.  Captures  areas  of  significant  waste-­‐water  disposal  wells  

RPSEA - 4D Integrated Multi-scale Reservoir and Geological Modeling

•  4D  geophysical  monitoring  •  Localized  well-­‐based  pressure  tests  •  Goals  –  Improve  model  predic$ve  capabili$es  – Maintain  a  suite  of  progressively  updated  models  –  Improved  representa$on  of  the  preferen$al  flowpaths  

– Geomechanical  proper$es  and  fault  characteris$cs  in  the  subsurface      

OKRaH Seismic Network

3D geologic and geophysical model

Geospa$ally  referenced  surfaces  Hunton  (orange)  and  basement  (brown).      Geologic  units  are  assigned  physical  proper$es  such  as  from  well  logs  with  spa$ally  varying  proper$es  such  as  permeability,  density,  porosity,  and  velocity.  

•  100,000’s  of  Wells  in  central  Oklahoma  

•  Geological  and  geophysical  logs  combined  to  build  3D  models  

•  Incorporated  into  3D  seismic  velocity  models  

Gravity Observations Provide Constraints on Geologic Models

All Submitted Faults

Industry  Contribu$ng  to  Enhanced  Fault  Database  

Interagency Cooperation

Industry,  DOE  and  

State  of  OK  Support  

OGS  Data  OCC  UIC  Program  

New  Permit  &  Exis$ng  Permits  

Fault  Maps  Earthquake  Informa$on  

Op$mally  Oriented  Faults  

Fault  Database  Project  

Industry  Fault  Database  

Contributors  &  OIPA  

Earthquake  Monitoring  and  

Repor$ng  

Improvements  to  Seismograph  Network  

Injec$on  and  Opera$onal  Data   Addi$onal  Studies  

Reservoir  &  Geomechanical  Modeling  RPSEA  

Current Mitigation Steps •  Oklahoma  Corpora$on  Commission  is  the  regulator  of  UIC  Class  II  wells,  and  have  implemented  different  mi$ga$on  strategies  – New  rules  regarding  repor$ng  of  injec$on  volumes  and  pressures  in  the  “Arbuckle”  

–  Permit  modifica$ons;  i.e.  “Traffic  Light  System”  –  Enhanced  repor$ng  requirements  in  OCC  areas  of  interest,  currently  10  km  around  ML  4+  earthquakes    •  Not  required  by  rule  for  non-­‐Arbuckle  wells,  but  operators  have  complied  for  requests  of  greater  repor$ng  

– New  permits  are  checked  against  fault  maps  and  background  seismicity  

Summary

•  The  rate  of  seismicity  has  increased  drama$cally  and  so  has  the  seismic  hazard  

•  Building  large  geological  and  geophysical  data  sets  at  varying  scales  and  dimensions  

•  Con$nue  to  provide  data  products  to  stakeholders  and  iden$fying  new  data  sources  

•  A  greater  understanding  of  physical  processes  in  Oklahoma  will  help  to  inform  future  mi$ga$on  strategies  

•  Mul$-­‐agency  coopera$on  has  now  been  solidified  in  the  governor’s  Coordina$ng  Council  

Abstract Oklahoma  has  experienced  a  very  significant  increase  in  seismicity  rates  over  the  last  5  years  with  the  greatest  increase  occurring  in  2014.    The  observed  rate  increase  indicates  that  the  seismic  hazard  for  at  least  some  parts  of  Oklahoma  has  increased  significantly.    Many  seismologists  consider  the  large  number  of  salt-­‐water  disposal  wells  opera$ng  in  Oklahoma  as  the  largest  contribu$ng  factor  to  this  increase.  However,  unlike  many  cases  of  seismicity  induced  by  injec$on,  the  greatest  increase  is  occurring  over  a  very  large  area,  about  15%  of  the  state.    There  are  more  than  3,000  disposal  wells  currently  opera$ng  within  Oklahoma  along  with  injec$on  volumes  greater  than  2010  rates.    These  factors  add  many  significant  challenges  to  iden$fying  poten$al  cases  of  induced  seismicity  and  understanding  the  contribu$ng  factors  well  enough  to  mi$gate  such  occurrences.    In  response  to  a  clear  need  for  a  bener  geotechnical  understanding  of  what  is  occurring  in  Oklahoma,  a  mul$-­‐year  mul$disciplinary  study  some  of  the  most  ac$ve  areas  has  begun  at  the  University  of  Oklahoma.    This  study  includes  addi$onal  seismic  monitoring,  bener  geological  and  geophysical  characteriza$on  of  the  subsurface,  hydrological  and  reservoir  modeling,  and  geomechanical  studies  to  bener  understand  the  rise  in  seismicity  rates.  The  Oklahoma  Corpora$on  Commission  has  added  new  rules  regarding  repor$ng  and  monitoring  of  salt-­‐water  disposal  wells,  and  con$nue  to  work  with  the  Oklahoma  Geological  Survey  and  other  researchers.